Efficiency of morphological, physiological and biochemical parameters related to sex expression in papaya

Abstract

The papaya (Carica papaya L.) is a polygamous plant, it has three types of sex forms, viz. male, female and hermaphrodite. The efforts were made to identify sex expression based on morphological, physiological and biochemical parameters. The matured plants were uniformly maintained for nutrition and intercultural operations in the nethouse and parameters were recorded accordingly. For the tabulation and data analysis, four genotypes were grouped in male (M), female (F) and hermaphrodite (H) making eight treatments, i.e., Pusa Nanha (F), Pusa Nanha (M), P-7-2 × SA M (F), P-7-2 × SA M (M), Red Lady (F), Red Lady (H), P-9-5 (F) and P-9-5 (H). Results showed that the maximum number of plants expressed their sex type in a range of 46-60° orientation of petiole, higher leaf chlorophyll ‘a’ content (2.573 mg/g f.wt.), in hermaphrodite sex plants in Red Lady and P-9-5 and lower levels in male plants. The phenolic content was significantly higher in the female plants followed by the hermaphrodite and male counterparts at seedling stage. The lowest total phenols content (29.25 and 39.50 mg/100 g f.wt.) was in hermaphrodite plants of Red Lady and P-9-5, respectively compared to female plants but higher than male plants among the dioecious genotypes at 10-leaf stage. The significant difference in total phenols content among hermaphrodite types was in Red Lady and P-9-5. Leaf gas exchange parameters were also indicative of sex expression at seedling stage. In female plants, the maximum stomatal conductance (0.523 mmol m-2s-1) was recorded in Red Lady followed by (0.353 mmol m-2s-1 in P-9-5 in comparison to hermaphrodite (0.435 mmol m-2s-1) plant in Red Lady followed by (0.280 mmol m-2s-1 in P-9- 5. However, minimum stomatal conductance was recorded in male plants. The higher stomatal conductance indicated feminism in papaya followed by hermaphrodite plants.